Aerodynamics

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Car designers must satisfy customers’ tastes while at the same time incorporating new technologies that improve aerodynamics. Aerodynamics is the physics that enables things to move through the air with minimal resistance, also called aerodynamic drag or wind resistance. Designers shape the outer body of cars to get the best aerodynamics and also design the interior to minimize the wind noise a vehicle creates when moving at high speed. The aerodynamic models sold today take into account both exterior and interior reactions of the vehicle with the air it moves through. The automobile industry uses computer modeling and wind tunnel testing to achieve the new model’s desired performance.

Aerodynamics engineering for cars focuses on two main components of drag: ground effects and rolling resistance. Ground effects are design features that reduce lift and wind resistance. Car designers shape a car so that more air flows smoothly over the car’s top than flows across the underside. Such a design also includes structures that reduce the turbulence of the air moving over the car and off the tail. In most vehicles the junction between the roof and rear window contributes to turbulence. For this reason new fixtures have been introduced to cut this turbulence and improve airflow, a process engineers call “tripping the airflow.” The following components trip the airflow on various new car models:

1. turbulator strips—thin metal strips that lessen the small layer of turbulence that occurs between any surface over which air flows
2. vortex generators—small teeth attached to the roof above the rear window to even the airflow speed over a vehicle
3. diffusers—undercarriage components that direct airflow away from the wheels to increase a downward force on a vehicle
4. shortened fairings—body parts that direct airflow around the tires